Excerpt from Charcot Arthropathy

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In 1703, William Musgrave first described a neuropathic joint as an arthralgia caused by venereal disease.¹ In 1868, Jean-Martin Charcot gave the first detailed description of the neuropathic aspect of this disease; hence, the condition is named after him.² Charcot noted this disease process as a complication of syphilis. Syphilis was believed to be the most common cause of Charcot arthropathy until 1936, when Jordan linked it to diabetes. Diabetes is now considered to be the most common etiology of Charcot arthropathy.

Problem

Also called Charcot joint or neuropathic joint, Charcot arthropathy is a progressive condition of the musculoskeletal system that is characterized by joint dislocations, pathologic fractures, and debilitating deformities. This disorder results in progressive destruction of bone and soft tissues at weight-bearing joints; in its most severe form, it may cause significant disruption of the bony architecture. Charcot arthropathy can occur at any joint; however, it occurs most commonly in the lower extremity, at the foot and ankle.

Frequency

The prevalence of Charcot arthropathy ranges from 0.1% to as high as 13% in specialized foot clinics. In patients with diabetes, the incidence of acute Charcot arthropathy of the foot and ankle ranges from 0.15-2.5%.

Epidemiologic studies do not distinguish between acute and postacute disease. Bilateral disease occurs in less than 10% of patients. Recurrence of disease occurs in less than 5% of patients. Some studies indicate that men and women are equally affected, while others report a 3:1 predilection for males.

Etiology

Any condition that causes sensory or autonomic neuropathy can lead to a Charcot joint. Charcot arthropathy occurs as a complication of diabetes, syphilis, chronic alcoholism, leprosy, meningomyelocele, spinal cord injury, syringomyelia, renal dialysis, and congenital insensitivity to pain. Diabetes is considered to be the most common cause of Charcot arthropathy.

Pathophysiology

The exact nature of Charcot arthropathy remains unknown, but the following major theories exist regarding the pathophysiology of this condition:

• Neurotraumatic theory - This theory states that Charcot arthropathy is caused by an unperceived trauma or injury to an insensate foot. The sensory neuropathy renders the patient unaware of the osseous destruction that occurs with ambulation. This microtrauma leads to progressive destruction and damage to bone and joints.
• Neurovascular theory - This theory suggests that the underlying condition leads to the development of autonomic neuropathy, causing the extremity to receive an increased blood flow. This in turn results in a mismatch in bone destruction and synthesis, leading to osteopenia.

Charcot arthropathy most likely results from a combination of the processes described in the above theories. The autonomic neuropathy leads to abnormal bone formation, and the sensory neuropathy leads to an insensate joint that is susceptible to trauma. The development of abnormal bone with no ability to protect the joint results in gradual bone fracture and in the subluxation of the joint.

Clinical

The clinical presentation of Charcot arthropathy can vary widely depending on the stage of the disease. Thus, symptoms can range from mild swelling and no deformity to moderate deformity with significant swelling.

Acute Charcot arthropathy almost always presents with signs of inflammation. Profound unilateral swelling, an increase in local skin temperature (generally, an increase of 3-7º above the nonaffected foot's skin temperature), erythema, joint effusion, and bone resorption in an insensate foot are present. These characteristics, in the presence of intact skin and a loss of protective sensation, are often pathognomonic of acute Charcot arthropathy.

Pain can occur in more than 75% of patients; however, the pain's severity is significantly less than would be expected based on the severity of the clinical and/or radiographic findings. Instability and loss of joint function also may be present. Passive movement of the joint may reveal a "loose bag of bones." Approximately 40% of patients with acute Charcot arthropathy have concomitant ulceration, which complicates the diagnosis and raises concerns that osteomyelitis is present.

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